A method for preparing a rubber tube for an automobile

Abstract

This invention discloses a method for preparing automotive rubber hoses, relating to the field of automotive rubber hose preparation technology, specifically including the following steps: preparation of rubber compound formulation, rubber compound mixing, pretreatment of reinforcing layer (2), extrusion molding, vulcanization treatment, finishing and testing. This method for preparing automotive rubber hoses, through the improved rubber compound formulations of the inner rubber layer (1) and outer rubber layer (3), uses a mixture of two EPDMs with different Mooney viscosities as the main material of the inner rubber layer (1), combined with a peroxide vulcanizing agent, to form high-bond-energy C-C crosslinking bonds, significantly improving the high and low temperature resistance of the hose, expanding the applicable temperature range of the hose, with a low-temperature compression set of ≤70% at -40℃, and no aging or cracking after long-term use in high-temperature environments. Furthermore, the outer rubber layer (3) uses a blend of EPDM and CR, and adds C10 series petroleum resin, effectively improving the polarity difference between the two rubbers, and enhancing the weather resistance, ozone resistance, and adhesion strength of the outer rubber layer (3) to the reinforcing layer (2).

Description

Technical Field

[0001] This invention relates to the field of automotive rubber hose manufacturing technology, specifically a method for manufacturing automotive rubber hoses. Background Technology

[0002] Automotive rubber hoses are core components of automotive chassis, engine, and body systems, responsible for transporting media such as coolant, fuel, and brake fluid. Their performance directly affects the vehicle's driving safety and reliability. As the automotive industry moves towards lightweighting and high durability, the requirements for rubber hoses are becoming increasingly stringent. They not only need to possess good resistance to media and high and low temperatures, but also high mechanical strength and interlayer adhesion strength.

[0003] In existing technologies, automotive rubber hoses are mostly made from single rubber materials or simple blends, resulting in insufficient adhesion strength between the inner and outer rubber layers and reinforcing layers, easily leading to delamination and debonding. Furthermore, hoses prepared using traditional sulfur vulcanization processes exhibit poor cross-linking stability, making them prone to aging and cracking under high-temperature (above 150℃) or low-temperature (below -40℃) conditions, leading to decreased sealing performance and shortened service life. In addition, unreasonable rubber mixing process parameters in some hose preparation processes result in uneven rubber compounding, further affecting the overall performance of the hose. For example, in existing technologies using nitrile rubber and neoprene rubber blends, the polarity difference between the two rubbers leads to low interlayer adhesion strength, making it difficult to meet the requirements of long-term automotive operation. Sulfur-vulcanized EPDM rubber hoses are prone to vulcanization network chain breakage under high-temperature conditions and excessive compression set under low-temperature conditions, resulting in a narrow applicable temperature range. Therefore, we propose a new method for preparing automotive rubber hoses. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing automotive rubber hoses, which solves the problems mentioned in the background section.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing automotive rubber hoses, comprising a rubber hose, wherein the rubber hose comprises, from the inside out, an inner rubber layer, a reinforcing layer, and an outer rubber layer, comprising the following steps: S1: Preparation of rubber compound formulation. The inner rubber layer and outer rubber layer are mixed according to their respective formulations. The inner rubber layer includes, by mass parts: 100 parts of EPDM rubber, 80-100 parts of reinforcing filler, 3-5 parts of peroxide vulcanizing agent, 30-35 parts of softening plasticizer, 3-5 parts of antioxidant, 2-3 parts of crosslinking aid, and 2-5 parts of C10 petroleum resin. The outer rubber layer comprises, by weight parts: 70-80 parts of EPDM rubber, 20-30 parts of chloroprene rubber, 100-110 parts of reinforcing filler, 2-4 parts of peroxide vulcanizing agent, 25-30 parts of softening plasticizer, 3-5 parts of antioxidant, 2-3 parts of crosslinking aid, and 2-5 parts of C10 petroleum resin. S2: Rubber compounding, adopting a two-stage mixing process, mixing the inner rubber layer and the outer rubber layer separately. The first stage discharge temperature is 120±10℃, and the second stage discharge temperature is 100±10℃. After mixing, the rubber is sheeted out and cooled for later use. S3: Reinforcing layer pretreatment, using polyester fiber cord, which is woven into shape after being soaked in pretreatment solution and dried; S4: Extrusion molding, using a three-layer co-extrusion process, simultaneously extruding the inner rubber layer, reinforcing layer, and outer rubber layer, controlling the extrusion temperature at 50℃, with the inner rubber layer thickness being 1.5-2.5mm and the outer rubber layer thickness being 1.0-2.0mm; S5: Vulcanization treatment, using tank vulcanization process, after vacuum pretreatment, control the vulcanization temperature at 170-175℃, vulcanization pressure at 1.2-1.5MPa, vulcanization time at 20-25min, and then allow it to cool naturally after vulcanization; S6: Trimming and Inspection. After vulcanization, the rubber hoses are trimmed, beautified, aged, and inspected. Once the products are qualified, they are packaged and stored in the warehouse.

[0006] Preferably, in S1, the EPDM rubber of the inner rubber layer is composed of 70-80 parts of first EPDM and 20-30 parts of second EPDM, the first EPDM has a Mooney viscosity of 65-80 and an ethylene content of 40%-50%, and the second EPDM has a Mooney viscosity of 25-30.

[0007] Preferably, the reinforcing filler of the inner adhesive layer is a mixture of semi-reinforcing carbon black N774 and fast-extrusion carbon black N550 in a 1:1 ratio, and the reinforcing filler of the outer adhesive layer is a mixture of carbon black CF602 and CSDPF2000 in a 3:2 ratio.

[0008] Preferably, the peroxide curing agent is di-tert-butyl peroxide dicumylbenzene, the softening plasticizer of the inner adhesive layer is liquid paraffin, the softening plasticizer of the outer adhesive layer is coumarone resin, the antioxidant is antioxidant RD and antioxidant 4020 mixed in a 2:1 ratio, and the crosslinking aid is zinc oxide, stearic acid and triallyl cyanurate mixed in a 1:1.5:0.5 ratio.

[0009] 5. The method for preparing automotive rubber hoses according to claim 1, characterized in that: the two-stage mixing process in S2 is specifically as follows: the first stage mixing temperature is 110-120℃, the rotation speed is 50-60r / min, and the mixing time is 3-8min; the second stage mixing temperature is 90-100℃, the rotation speed is 40-50r / min, and the mixing time is 4-6min; after mixing, the material is passed through a two-roll mill 3-4 times to produce a sheet thickness of 2-3mm.

[0010] Preferably, in step S3, the pretreatment solution is a mixture of silane coupling agent KH-550, ethanol, and water in a volume ratio of 1:8:1. The cord soaking time is 10-15 minutes, the drying temperature is 120-130℃, the drying time is 20-30 minutes, the moisture content of the cord after drying is ≤0.5%, the weaving density is 80-100 cords / 10cm, and the weaving angle is 45°±5°.

[0011] Preferably, the extrusion speed in S4 is 1-2 m / min, and the traction speed is synchronized with the extrusion speed.

[0012] Preferably, the vacuum pretreatment pressure in S5 is -0.08 to -0.09 MPa, the time is 5 to 10 minutes, and the vulcanization is completed and then naturally cooled.

[0013] Preferably, the aging treatment conditions in S6 are 23±2℃, relative humidity 50±5%, and treatment time is 24h.

[0014] Preferably, the test items in S6 include interlayer adhesion strength, tensile strength, high and low temperature resistance, and aging resistance.

[0015] This invention provides a method for preparing automotive rubber hoses, which has the following beneficial effects: 1. This method for preparing automotive rubber hoses, through improved formulations of the inner and outer rubber layers, uses a mixture of two EPDMs with different Mooney viscosities as the main material for the inner rubber layer, combined with a peroxide vulcanizing agent, to form high-energy CC crosslinks, significantly improving the hose's high and low temperature resistance and expanding its applicable temperature range. At -40℃, the compression set is ≤70%, and there is no aging or cracking after long-term use in high-temperature environments. Furthermore, the outer rubber layer uses a blend of EPDM and CR, with the addition of C10 series petroleum resin, effectively improving the polarity difference between the two rubbers and enhancing the outer rubber layer's weather resistance, ozone resistance, and adhesion strength to the reinforcing layer.

[0016] 2. This method for preparing automotive rubber hoses employs a two-stage mixing process, strictly controlling the mixing temperature, speed, and time of each stage to ensure uniform mixing of all components in the rubber compound, avoiding local component aggregation, and improving the processing and mechanical properties of the rubber compound. Simultaneously, the reinforcing cord is pretreated with a silane coupling agent, enhancing the interfacial bonding between the cord and the rubber compound. This effectively solves the technical problems of interlayer delamination and debonding in the hose, achieving an interlayer adhesion strength ≥1.5 N / mm, meeting the requirements of long-term automotive operation.

[0017] 3. The method for preparing automotive rubber hoses employs a three-layer co-extrusion molding process to simultaneously complete the molding of the inner rubber layer, reinforcing layer, and outer rubber layer, ensuring a tight fit between each layer without gaps or wrinkles; precise control of vulcanization process parameters and vacuum pretreatment to remove air from the tube blank prevent the generation of bubbles during vulcanization, thereby improving the tightness and sealing performance of the hose. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the automotive rubber hose of the present invention; Figure 2 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0020] Example 1 Please see Figures 1 to 2 This invention provides a technical solution: a method for preparing automotive rubber hoses, wherein the rubber hose is composed of an inner rubber layer 1, a reinforcing layer 2, and an outer rubber layer 3 from the inside out, and includes the following preparation steps: S1: Rubber compound formulation preparation The rubber compound formulation of the inner layer 1 of S1.1, by weight, includes: 100 parts EPDM (75 parts of the first EPDM, Mooney viscosity 70, ethylene content 45%; 25 parts of the second EPDM, Mooney viscosity 28), 90 parts reinforcing filler (45 parts of N774, 45 parts of N550), 4 parts di-tert-butyl peroxide dicumyl peroxide, 32 parts liquid paraffin, 4 parts antioxidant (2.7 parts of RD, 1.3 parts of 4020), 2.5 parts crosslinking aid (1 part zinc oxide, 1.5 parts stearic acid, 0.5 parts TAC), and 3 parts C10 series petroleum resin; S1.2 Outer Layer 3 Rubber Compound Formulation (by weight): 75 parts EPDM, 25 parts CR, 105 parts reinforcing filler (63 parts CF602, 42 parts CSDPF2000), 3 parts di-tert-butyl peroxide diisopropylbenzene, 28 parts coumarone resin, 4 parts antioxidant (2.7 parts RD, 1.3 parts 4020), 2.5 parts crosslinking aid (1 part zinc oxide, 1.5 parts stearic acid, 0.5 parts TAC), 3 parts C10 series petroleum resin; S2: Rubber compounding S2.1: First stage of mixing: Put the raw rubber of inner layer 1 into the internal mixer, temperature 115℃, speed 55r / min, mix for 4min; add reinforcing filler, liquid paraffin and antioxidant, continue to mix for 6min, discharge temperature 120℃, to obtain the first stage of compound rubber. S2.2: Second stage mixing: Cool the first stage compound to room temperature, put it into an internal mixer at 95°C and 45 r / min, add peroxide vulcanizing agent, crosslinking aid and C10 series petroleum resin, mix for 5 min, discharge temperature 100°C, to obtain the second stage compound. S2.3: Post-mixing treatment: The two-stage mixed rubber is fed into the open mill, the roller temperature is 45℃, and it is passed through the thin mill 3 times to produce a sheet thickness of 2.5mm. It is then cooled and set aside. The mixing process of the outer rubber layer 3 is the same as that of the inner rubber layer 1. S3: Preprocessing of Enhancement Layer 2 Polyester fiber cords were used and immersed in a pretreatment solution (silane coupling agent KH-550: ethanol: water = 1:8:1) for 12 minutes, and then dried in an oven at 125℃ for 25 minutes. The moisture content after drying was 0.4%. The cords were then woven using a braiding machine with a braiding density of 90 cords / 10cm and a braiding angle of 45°. S4: Extrusion Molding The material is produced by three-layer co-extrusion molding, with each section extruded at 50℃. The inner rubber layer 1 is 2.0mm thick, and the outer rubber layer 3 is 1.5mm thick. The reinforcing layer 2 is wound synchronously, with an extrusion speed of 1.5m / min and the traction speed being synchronized with the extrusion speed. S5: Vulcanization treatment The tube blank is placed in a vulcanizing tank, and a vacuum is drawn to -0.085 MPa and maintained for 8 minutes. High-pressure steam is then introduced, and the vulcanization temperature is 172℃, the vulcanization pressure is 1.3 MPa, and the vulcanization time is 22 minutes. After vulcanization, the tube blank is allowed to cool naturally to room temperature. S6: Trimming and testing: After trimming, the material is aged for 24 hours at 23℃ and 50% relative humidity. Test results: interlayer adhesion strength 1.8 N / mm, tensile strength 19.5 MPa, elongation at break 480%, low-temperature compression set at -40℃ 65%, after aging in hot air at 150℃ for 240 hours, tensile strength change rate 30%, elongation at break change rate 60%, and hardness change value 12, all of which meet the requirements for use in automotive rubber hoses.

[0021] Example 2 In this embodiment, please refer to Figures 1 to 2 This invention provides a technical solution: a method for preparing automotive rubber hoses, wherein the rubber hose is composed of an inner rubber layer 1, a reinforcing layer 2, and an outer rubber layer 3 from the inside out, and includes the following preparation steps: S1: Rubber compound formulation preparation S1.1: Rubber compound formulation for inner layer 1 (by mass parts): 100 parts EPDM (70 parts first EPDM, Mooney viscosity 65, ethylene content 40%; 30 parts second EPDM, Mooney viscosity 25), 80 parts reinforcing filler (40 parts N774, 40 parts N550), 3 parts di-tert-butyl peroxide dicumyl peroxide, 30 parts liquid paraffin, 3 parts antioxidant (2 parts RD, 1 part 4020), 2 parts crosslinking aid (1 part zinc oxide, 1.5 parts stearic acid, 0.5 parts TAC), 2 parts C10 petroleum resin; S1.2: The formula of the outer adhesive layer 3 (by weight parts): 70 parts EPDM, 30 parts CR, 100 parts reinforcing filler (60 parts CF602, 40 parts CSDPF2000), 2 parts di-tert-butyl peroxide diisopropylbenzene, 25 parts coumarone resin, 3 parts antioxidant (2 parts RD, 1 part 4020), 2 parts crosslinking aid (1 part zinc oxide, 1.5 parts stearic acid, 0.5 parts TAC), and 2 parts C10 petroleum resin; S2: Rubber compounding S2.1: First stage of mixing: Put the raw rubber of inner layer 1 into the internal mixer, temperature 110℃, speed 50r / min, mix for 3min; add reinforcing filler, liquid paraffin and antioxidant, continue to mix for 5min, discharge temperature 110℃, to obtain the first stage of compound rubber. S2.2: Second stage mixing: Cool the first stage compound to room temperature, put it into an internal mixer, add peroxide vulcanizing agent, crosslinking aid and C10 series petroleum resin at 90℃ and 40r / min, mix for 4min, discharge the compound at 90℃ to obtain the second stage compound. S2.3: Post-mixing treatment: The two-stage mixed rubber is fed into the open mill, the roller temperature is 40℃, and it is passed through the thin mill 3 times to produce a sheet thickness of 2mm. It is then cooled and set aside for later use. The mixing process of the outer rubber layer 3 is the same as that of the inner rubber layer 1. S3: Reinforcing layer 2 pretreatment: Polyester fiber cord is used, which is immersed in pretreatment solution (silane coupling agent KH-550: ethanol: water = 1:8:1) for 10 minutes, and then dried in an oven at 120℃ for 20 minutes. The moisture content after drying is 0.3%. It is woven by a braiding machine with a braiding density of 80 strands / 10cm and a braiding angle of 40°. S4: Extrusion Molding The material is produced by three-layer co-extrusion molding, with each section extruded at 50℃. The inner rubber layer 1 is 1.5mm thick, and the outer rubber layer 3 is 1.0mm thick. The reinforcing layer 2 is wound synchronously, with an extrusion speed of 1m / min and the traction speed being synchronized with the extrusion speed. S5: Vulcanization treatment Place the tube blank into a vulcanizing tank, evacuate to -0.08MPa and maintain for 5 minutes; introduce high-pressure steam, vulcanize at 170℃, vulcanize at 1.2MPa and vulcanize for 20 minutes; after vulcanization, allow it to cool naturally to room temperature. S6: Trimming and Inspection After trimming, the material was aged for 24 hours at 23℃ and 50% relative humidity. Test results showed that the interlayer bonding strength was 1.6 N / mm, the tensile strength was 18.2 MPa, the elongation at break was 450%, the compression set at -40℃ was 68%, and after aging in hot air at 150℃ for 240 hours, the change rate of tensile strength was 32%, the change rate of elongation at break was 62%, and the change in hardness was 10, all of which met the requirements for use in automotive rubber hoses.

[0022] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an automotive rubber hose, comprising a rubber hose, characterized in that: The rubber hose comprises, from the inside out, an inner rubber layer (1), a reinforcing layer (2), and an outer rubber layer (3), and includes the following steps: S1: Rubber compound preparation, the rubber compounds of the inner rubber layer (1) and the outer rubber layer (3) are mixed according to the corresponding formulas, wherein the rubber compound of the inner rubber layer (1) includes, by mass parts: 100 parts of EPDM rubber, 80-100 parts of reinforcing filler, 3-5 parts of peroxide vulcanizing agent, 30-35 parts of softening plasticizer, 3-5 parts of antioxidant, 2-3 parts of crosslinking aid, and 2-5 parts of C10 petroleum resin; The outer rubber layer (3) comprises, by weight parts: 70-80 parts of EPDM rubber, 20-30 parts of chloroprene rubber, 100-110 parts of reinforcing filler, 2-4 parts of peroxide vulcanizing agent, 25-30 parts of softening plasticizer, 3-5 parts of antioxidant, 2-3 parts of crosslinking aid, and 2-5 parts of C10 petroleum resin; S2: Rubber compounding, adopting a two-stage mixing process, mixing the inner rubber layer (1) rubber compound and the outer rubber layer (3) rubber compound respectively. The first stage discharge temperature is 120±10℃, and the second stage discharge temperature is 100±10℃. After mixing, the sheet is cooled for later use. S3: Reinforcing layer (2) pretreatment, using polyester fiber cord, which is woven into shape after being soaked in pretreatment liquid and dried; S4: Extrusion molding, using a three-layer co-extrusion process, the inner rubber layer (1), the reinforcing layer (2) and the outer rubber layer (3) are extruded simultaneously, the extrusion temperature is controlled at 50℃, the thickness of the inner rubber layer (1) is 1.5-2.5mm, and the thickness of the outer rubber layer (3) is 1.0-2.0mm; S5: Vulcanization treatment, using tank vulcanization process, after vacuum pretreatment, control the vulcanization temperature at 170-175℃, vulcanization pressure at 1.2-1.5MPa, vulcanization time at 20-25min, and then allow it to cool naturally after vulcanization; S6: Trimming and Inspection. After vulcanization, the rubber hoses are trimmed, beautified, aged, and inspected. Once the products are qualified, they are packaged and stored in the warehouse.

2. The method for preparing an automotive rubber hose according to claim 1, characterized in that: In S1, the EPDM rubber of the inner rubber layer (1) is composed of 70-80 parts of first EPDM and 20-30 parts of second EPDM. The first EPDM has a Mooney viscosity of 65-80 and an ethylene content of 40%-50%. The second EPDM has a Mooney viscosity of 25-30.

3. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The reinforcing filler of the inner adhesive layer (1) is a mixture of semi-reinforcing carbon black N774 and fast extrusion carbon black N550 in a 1:1 ratio, and the reinforcing filler of the outer adhesive layer (3) is a mixture of carbon black CF602 and CSDPF2000 in a 3:2 ratio.

4. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The peroxide vulcanizing agent is di-tert-butyl peroxide diisopropylbenzene, the softening plasticizer of the inner layer (1) is liquid paraffin, the softening plasticizer of the outer layer (3) is coumarone resin, the antioxidant is antioxidant RD and antioxidant 4020 mixed in a 2:1 ratio, and the crosslinking aid is zinc oxide, stearic acid and triallyl cyanurate mixed in a 1:1.5:0.5 ratio.

5. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The two-stage mixing process in S2 is as follows: the first stage mixing temperature is 110-120℃, the rotation speed is 50-60r / min, and the mixing time is 3-8min; the second stage mixing temperature is 90-100℃, the rotation speed is 40-50r / min, and the mixing time is 4-6min. After mixing, the sheet is passed through a two-roll mill 3-4 times, and the sheet thickness is 2-3mm.

6. The method for preparing an automotive rubber hose according to claim 1, characterized in that: In step S3, the pretreatment solution is a mixture of silane coupling agent KH-550, ethanol, and water in a volume ratio of 1:8:

1. The cord is soaked for 10-15 minutes, dried at 120-130°C for 20-30 minutes, and the moisture content of the cord after drying is ≤0.5%, the weaving density is 80-100 cords / 10cm, and the weaving angle is 45°±5°.

7. The preparation method according to claim 1, characterized in that, The extrusion speed in S4 is 1-2 m / min, and the traction speed is synchronized with the extrusion speed.

8. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The vacuum pretreatment pressure in S5 is -0.08 to -0.09 MPa, and the time is 5 to 10 minutes. After vulcanization is completed, the system naturally cools down.

9. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The aging conditions in S6 are 23±2℃, relative humidity 50±5%, and the treatment time is 24h.

10. The method for preparing an automotive rubber hose according to claim 1, characterized in that: The testing items in S6 include interlayer adhesion strength, tensile strength, high and low temperature resistance, and aging resistance.

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